1. Field of the Invention
The present invention relates to a retractable step assembly that may be mounted to a vehicle.
2. Description of Related Art
Steps that are stowable, or retractable, on vehicles have been developed to aid a person to access parts of the vehicle that would otherwise be difficult to access. Designs to achieve this stowability are numerous, but may be characterized by a small number of articulated motions, including rectilinear and rotational. Steps that move rectilinearly between the stowed and deployed positions operate much like drawers in a cabinet, as disclosed in, for example, U.S. Pat. No. 6,036,208. To deploy the step, the user pulls one end of the step out from the vehicle. To store the step, the user pushes the step in towards the vehicle until it is stowed. This type of step requires the balancing of mounting the step high enough so that the step provides adequate ground clearance, yet low enough so a user of an average height may easily use the step when it is deployed.
Steps that move rotationally typically rotate about either a substantially horizontal axis or a substantially vertical axis. Steps that pivot about a substantially horizontal axis, as disclosed in, for example, U.S. Pat. No. 4,462,486, operate like a tailgate of a pick-up truck. When the user wants to deploy the step, user pulls the step down to a substantially horizontal position. To store the step, the user rotates the step to a non-horizontal, typically substantially vertical, position. Like the steps that move rectilinearly, as described above, these steps should also be carefully mounted on the vehicle.
Steps that rotate about a substantially vertical axis, as disclosed in, for example, U.S. Pat. No. 5,897,125, are typically stored in a position beneath a part of the vehicle, and are rotated to be deployed in a position away from the vehicle. Again, these steps should be carefully mounted so that sufficient ground clearance is provided, as well as an easy to use height.
U.S. Pat. No. 4,312,515 discloses a step that moves both rotationally about and rectilinearly along a substantially vertical axis when it is moved between the stowed and deployed positions. A slot that is substantially vertical is used to “lock” the step in a deployed position. A cam slot that is disposed at an angle from the vertical axis defines the motion of the step when it moves into the stowed position. This motion is both rotational and rectilinear, as movement of a pin that is operatively connected to the step along the cam slot causes the step to rotate about the vertical axis and translate along the vertical axis. This cam slot is used to “lock” the step in the stowed position. To move the step from the stowed position, the user lifts and rotates the step until the pin reaches the top of the vertical slot, then allows gravity to act on the step, and, hence, the pin moves down the vertical slot and into the “locked” deployed position. To stow the step, the user lifts the step so that the pin moves out of the vertical slot, then rotates the step away from the vertical slot. Again, gravity will act on the step and allow the pin to move to the bottom of the cam slot, thereby “locking” the step in the stowed position.
None of the aforementioned examples have mechanisms that are protected from adverse environmental conditions. In each of these examples, the mechanisms that provide the motion, as well as any locking structure, are exposed to the environment, which may cause the mechanisms to get wet and dirty, thereby subjecting them to potential corrosion and/or mechanical malfunctions.